Currently, common naked-eye three-dimensional (3D) display devices are mainly divided into a parallax barrier type and a lenticular lens type. The basic principle thereof is to divide an image into a left-eye image and a right-eye image, and after the left-eye image and the right-eye image are transmitted through a parallax barrier or a lenticular lens, a plurality of left viewing regions and right viewing regions arranged alternately are presented in front of a display panel. When a left eye of a viewer is in the left viewing region and a right eye of the viewer is in the right viewing region, the left eye of the viewer can see the corresponding left-eye image, and the right eye can see the corresponding right-eye image. The left-eye image and the right-eye image are a pair of stereoscopic images, thus, the brain may combine them into a 3D image, so as to produce 3D display effect.
However, when the viewer views the 3D image displayed by the above-described 3D display device, he or she has to be positioned at a certain position in front of the naked-eye 3D display device in order to see the 3D image with better effect. Otherwise, the stereoscopic effect is poor, even no stereoscopic effect is obtained at all.